A. Field of the Invention
The present invention relates to a method for controlling the flash of a camera. More particularly, the present invention relates to a method for controlling the flash of an interline charge coupled device (CCD) camera.
B. Description of the Prior Art
In general terms, an interline CCD camera is a digital camera using an interlace method. According to this method, the camera takes two photographs of an image and then forms one frame by synthesizing the two photograph fields. Since it usually takes no more than 1/60 of a second to photograph an image, the period for one frame is 1/30 of a second. When the interline CCD camera uses a flash, the flash is normally set to emit light once during a predetermined emitting time for each frame period. However, the maximum duration of a typical flash is about 3 ms, much shorter than a frame period (1/30 second which equals about 33.3 ms). Furthermore, when the flash is used indoors or in a dark place, there will be differences in the amount of light between the two photograph fields. These differences cause lines to be generated in the photograph, thus deteriorating the quality of the final image.
To prevent this problem when the flash is used, only one photograph of an image is used to form a frame. However, this results in lowering the vertical resolution of the photograph as compared to when two photographs are used when there is no flash.